This invention relates to railroad car wheel mountings and more particularly to improve differential wheel and axle constructions.
Rail car differential wheel and axle constructions of various types have been disclosed in the prior art and patents which relate to such construction include: U.S. Pat. No. 201,726, dated 1878 to Watkeys; U.S. Pat. No. 237,906, dated 1881, to Rhett; U.S. Pat. No. 1,292,663 to Thomas and U.S. Pat. No. 1,316,087 to Dowe. These patents disclose various differential wheel constructions for railroad cars in which one of a pair of rail car wheels is press-fitted onto an axial elongated sleeve rotatably mounted on a rail car axle. In this manner, the sleeve mounted wheel is free to rotate about the axle independently of another wheel which is press-fitted directly adjacent the other end of the axle. Among the drawbacks of these constructions are the difficulty of bearing lubrication, the fretting of the metal-to-metal bearing surfaces and the need for specialized and costly axle constructions.
The assembly disclosed in Johnson U.S. Pat. No. 3,321,232, issued in May 1967, involves a completely separate short axle mounted onto the end of a longer axle. A full length hollow cylindrical axle is supported on both ends by roller bearings and the short axle is attached to one end of the hollow axle. This arrangement is complicated and very costly.
It is the principal object of this invention to provide differential railroad wheel and axle constructions which overcome the drawbacks of the prior art.
It is another object of this invention to provide a method for adapting conventional railroad axles for use in differential wheel and axle combination which meet the standards of the Association of American Railroads (AAR).
It is a further object of this invention to provide a differential wheel and axle construction which relieves the stresses in the wheel-to-axle interface and eliminates steel-to-steel surface rubbing contact subject to fretting.
It is still a further object of this invention to provide differential wheel and axle constructions which overcome the problems of fretting corrosion, brinelling failure and which are capable of resisting lateral forces caused by rail-on-wheel thrust.